1. Field
Aspects of embodiments of the present invention relate to a system for rolling electrode plates.
2. Description of the Related Art
Batteries, such as lithium ion polymer batteries, are manufactured in various shapes, including, for example, cylindrical, prismatic, and pouch. The shapes of the batteries may be determined according to factors such as the shapes of corresponding products employing the batteries. For example, batteries for use in automobiles may require high-capacity, high-output characteristics, and may include an electrode assembly and an electrolyte accommodated in a prismatic can.
In order to manufacture a high-capacity battery, it may be desired to wind as many electrode plates as possible into a can having a given volume. In addition, in order to increase amounts of active materials coated on the electrode plates, it may be desired to reduce the volume occupied by current collectors in the can. However, since current collecting efficiency should be maintained to manufacture a high-output battery, the battery may be manufactured by forming electrode tabs on the electrode plates at regular intervals, such as every turn, level, or winding of the electrode assembly. Each such turn, level, or winding of the electrode assembly may then have its corresponding tabs for connecting to the current collectors of the electrode plate in consistent locations so that the tabs line up in the electrode assembly. The thus manufactured electrode assembly is referred to as a multi-tab electrode assembly.
The multi-tab electrode assembly may be manufactured by rolling a positive electrode plate and a second electrode plate with separators interposed therebetween using a rolling apparatus to prevent the positive electrode plate and the negative electrode plate from being electrically short-circuited. In addition, a notching apparatus may be employed to form an electrode tab having a particular shape on each of the positive electrode plate and the negative electrode plate.
The notching apparatus may include an unwinder, a punch, and a winder, and may punch a base material (of the electrode plates) supplied in a reel to a desired shape. The notching apparatus may then wind the punched base material into a reel to deliver to a subsequent process stage.
As described above, the notching apparatus and the rolling apparatus may be required to manufacture the multi-tab electrode assembly. First, for both the positive electrode plate and the negative electrode plate, a reel having a corresponding base material wound thereon is installed on the unwinder of the notching apparatus, and the base material is then supplied to the punch to form the electrode tab of the desired shape on each of the positive electrode plate and the negative electrode plate. This may be followed by rolling the formed electrode tabs in a reel using the winder for the positive electrode plate and for the negative electrode plate. The thus formed reels are transferred to the rolling apparatus, and the rolling apparatus rolls the positive electrode plate and the negative electrode plate each having the electrode tabs having a particular shape together with the separators to manufacture the multi-tab electrode assembly.
As described above, the electrode tabs are formed by the notching apparatus and the electrode assembly is rolled by the rolling apparatus. Therefore, in manufacturing a multi-tab electrode assembly, it may be quite difficult to properly align the positive or negative electrode tabs. In addition, when the electrode tabs are misaligned (as may be detected, for example, in the winder), it may be necessary to correct the misalignment of the electrode tabs, such as by modifying notching intervals of the notching apparatus. It may be necessary to check again whether the electrode tabs are properly aligned (such as in the winder), which may be quite a cumbersome process. Accordingly, it may take a long time to form high-quality electrode tabs and a considerable amount of base materials may be consumed.
In addition, if thicknesses of positive and negative electrode plates vary, the electrode tabs may get out of alignment, and the alignment of the electrode tabs may need to be corrected again. Further, in order to manufacture the multi-tab electrode assembly as described, two kinds of apparatuses may be required, which may increase the area for installing the apparatuses and may increase investment costs for the apparatuses.